Multiple CMS sites on same CMS database

Is it doable? Can we create multiple sites and manage these sites from one site manager?
You can only connect to only one database from your DCA but you can divide your channels under the main channel root to make sub channels like site1, site2 and from your code you can work in the first site with site1 as your root channel not channels root and make the same with the second site.
So you can create any number of sites under one CMS DB.